Control of surface morphology in PS and PVP hybrid thin films

Novel surface morphology in polymer thin films has been developed with a combination of polystyrene (PS) and poly(2-vinyl pyridine) (PVP) and characterized with optical microscope (OM) and atomic force microscope (AFM). In PS/PVP blend thin films, asymmetric phase separation in thin film is induced by the strong immiscibility between the constituent polymers and the different affinity for surface and the substrate. For inverted bilayer thin films, the rupture of the upper PVP layer initially occurs and the dewetting of the lower PS layer is then triggered and accelerated by the dewetted PVP layer. When thin films are prepared with PS-PVP diblocks, the dual morphology of islands and fractal holes is observed and found to be a kinetically trapped metastable structure induced by a residual solvent.